DOCSLIB.ORG

Barcoding Against a Paradox? Combined Molecular Species Delineations Reveal Multiple Cryptic Lineages in Elusive Meiofaunal

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Barcoding Against a Paradox? Combined Molecular Species Delineations Reveal Multiple Cryptic Lineages in Elusive Meiofaunal Jörger et al. BMC Evolutionary Biology 2012, 12:245 http://www.biomedcentral.com/1471-2148/12/245 RESEARCH ARTICLE Open Access Barcoding against a paradox? Combined molecular species delineations reveal multiple cryptic lineages in elusive meiofaunal sea slugs Katharina M Jörger1,2*, Jon L Norenburg3, Nerida G Wilson4 and Michael Schrödl1,2 Abstract Background: Many marine meiofaunal species are reported to have wide distributions, which creates a paradox considering their hypothesized low dispersal abilities. Correlated with this paradox is an especially high taxonomic deficit for meiofauna, partly related to a lower taxonomic effort and partly to a high number of putative cryptic species. Molecular-based species delineation and barcoding approaches have been advocated for meiofaunal biodiversity assessments to speed up description processes and uncover cryptic lineages. However, these approaches show sensitivity to sampling coverage (taxonomic and geographic) and the success rate has never been explored on mesopsammic Mollusca. Results: We collected the meiofaunal sea-slug Pontohedyle (Acochlidia, Heterobranchia) from 28 localities worldwide. With a traditional morphological approach, all specimens fall into two morphospecies. However, with a multi-marker genetic approach, we reveal multiple lineages that are reciprocally monophyletic on single and concatenated gene trees in phylogenetic analyses. These lineages are largely concordant with geographical and oceanographic parameters, leading to our primary species hypothesis (PSH). In parallel, we apply four independent methods of molecular based species delineation: General Mixed Yule Coalescent model (GMYC), statistical parsimony, Bayesian Species Delineation (BPP) and Automatic Barcode Gap Discovery (ABGD). The secondary species hypothesis (SSH) is gained by relying only on uncontradicted results of the different approaches (‘minimum consensus approach’), resulting in the discovery of a radiation of (at least) 12 mainly cryptic species, 9 of them new to science, some sympatric and some allopatric with respect to ocean boundaries. However, the meiofaunal paradox still persists in some Pontohedyle species identified here with wide coastal and trans-archipelago distributions. Conclusions: Our study confirms extensive, morphologically cryptic diversity among meiofauna and accentuates the taxonomic deficit that characterizes meiofauna research. We observe for Pontohedyle slugs a high degree of morphological simplicity and uniformity, which we expect might be a general rule for meiofauna. To tackle cryptic diversity in little explored and hard-to-sample invertebrate taxa, at present, a combined approach seems most promising, such as multi-marker-barcoding (i.e., molecular systematics using mitochondrial and nuclear markers and the criterion of reciprocal monophyly) combined with a minimum consensus approach across independent methods of molecular species delineation to define candidate species. * Correspondence: [email protected] 1Mollusca Department, Bavarian State Collection of Zoology, Münchhausenstr.21, 81247, München, Germany 2Department Biology II, Ludwig-Maximilians-Universität, BioZentrum Martinsried, Großhadernerstr. 2, 82152, Planegg-Martinsried, Germany Full list of author information is available at the end of the article © 2012 Jörger et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Jörger et al. BMC Evolutionary Biology 2012, 12:245 Page 2 of 18 http://www.biomedcentral.com/1471-2148/12/245 Background possible inadvertent inclusion of nuclear mitochondrial Sediment-associated marine meiofaunal organisms in- pseudogenes (= nonfunctional copies of mtDNA in the habit one of the largest ecosystems on earth – sediment- nucleus, or numts) [19], and other mitochondria-specific covered ocean floors and beaches – and comprise a pitfalls such as reduced effective population size or incon- major part of marine biodiversity [1]. However, only a sistent recombination [20]. The risk of incorrect species small fraction of the predicted species richness currently delineation due to incomplete lineage sorting or intro- is known to science [1-4] and recent surveys have shown gression can be reduced by analyzing independent loci a high number of new, undescribed species even in well- [21], which is generally considered superior to single- studied areas (see [4]). Minute body sizes often prohibit gene approaches [22]. We chose a barcoding approach direct visual identification in the field; instead, morpho- based on three molecular markers that have been de- logical identification generally requires time-consuming, monstrated to provide good resolution for species de- technologically sophisticated anatomical studies. Add- lineation in some Mollusca [23-25]. We included, in itionally, taxonomy frequently is complicated by mor- addition to mitochondrial Cytochrome c Oxidase subunit phological convergence and/or pronounced intraspecific I (COI) and 16S rRNA, nuclear 28S rRNA (large rib- variation (e.g., [3,5]). In Acochlidia, the most diverse osomal subunit – LSU), which has performed well for group of meiofaunal slugs, the Microhedylacea, shows species separation and was suggested as a signature ‘regressive evolution’ [6], exhibiting highly simplified gene fragment for a DNA taxonomy system for meio- organ systems and little morphological diversity even at benthos [8,26]. higher taxonomic levels [7]. Thus, it is challenging to Any method of species delineation is sensitive to use only morphology to delimit species boundaries in sampling [27], and rarity is almost universal when dealing meiofaunal slugs. In consequence of the fragmentary with invertebrates [28]. Rarity is not only a theoretical knowledge of meiofaunal taxonomy, this fauna is fre- problem in species delineation methods, but hinders as- quently neglected in conservation and biogeography, sessment of genetic variability [16,28]; if populations with and ecological analyses remain superficial despite the intermediate haplotype composition are left unsampled, undoubted importance of meiofauna; e.g., in the food barcoding and molecular-based species delineation ap- chain [8]. proaches tend to overestimate species [18,27]. With large For taxon-specific analyses, DNA-barcoding has been parts of the worldwide meiofauna still unexplored, and advocated as a fast and efficient way to reduce the taxo- patchy, discrete distributions being characteristic for nomic deficit and automate taxon determination for meiofaunal taxa [29], the present-day knowledge of this ecological research [3,5,8]. DNA-barcoding in its simple, fauna is prone to incomplete sampling. The rapidly similarity-based form of species identification [9] is not spreading biodiversity crisis with the destruction of habi- predictive; it fails if no identical sequence has yet been tats and high extinction rates calls for quick surveys and determined and deposited in a voucher database, or if realistic data for efficient conservation strategies (e.g., [16], no limit in species boundaries has been established and references therein). Currently, most molecular species [10,11]. In well-known taxa with good sampling cover- delineation approaches have been conducted on large age, identification rates via DNA-barcoding can be quite datasets with dense sampling coverage or on local scales successful (e.g.,[12,13]), but in case of meiofauna finding (e.g., [30-35]), with few exceptions using small datasets in identical sequences in public databases for a newly integrative approaches (e.g., [36]). Barcoding approaches collected mollusk or other under-investigated taxon is using COI trees for defining species clusters and revealing not expected to become the rule for decades to come. gaps between intra- and intercluster distance; multi-locus The application of the typical barcoding approach for tree-based methods with or without using diagnostic char- species delineation - COI in conjunction with a com- acters; and a couple of newly developed, tree-independent parison of pairwise distances - in Mollusca has resulted methods for species delineation, all serve as methods for in mixed reports: although the identification success DNA taxonomy. However, as a solution to address the with known taxa was generally high (e.g., [12,14,15]), the challenges of the taxonomic impediment in problematic determination of a ‘barcoding gap’ (i.e., significant differ- taxa the power of these methods is still largely untested. ence between inter- and intraspecific variation) and thus Here, we performed thorough phylogenetic analyses of a delimiting threshold has been problematic, especially all three molecular markers and integrate available add- above local-scale approaches and in undersampled phy- itional data from morphology and geography. In parallel, logenies [12]. Doubts have also arisen concerning spe- we applied four different methods of species delineation: cies identification and delimitation based on single-locus 1) The General Mixed Yule Coalescent model (GMYC) DNA sequences, which frequently result in problematic [32,33] is a maximum likelihood approach, able to dis- under- or overestimation of species [16-18]. Mitochon- criminate between population and speciation patterns drial markers, especially, came under criticism
Load more

Recommended publications
  • A Polyvalent and Universal Tool for Genomic Studies In
    A polyvalent and universal tool for genomic studies in gastropod molluscs (Heterobranchia: Tectipleura) Juan Moles1 and Gonzalo Giribet1 1Harvard University Faculty of Arts and Sciences April 28, 2020 Abstract Molluscs are the second most diverse animal phylum and heterobranch gastropods present ~44,000 species. These comprise fascinating creatures with a huge morphological and ecological disparity. Such great diversity comes with even larger phyloge- netic uncertainty and many taxa have been largely neglected in molecular assessments. Genomic tools have provided resolution to deep cladogenic events but generating large numbers of transcriptomes/genomes is expensive and usually requires fresh material. Here we leverage a target enrichment approach to design and synthesize a probe set based on available genomes and transcriptomes across Heterobranchia. Our probe set contains 57,606 70mer baits and targets a total of 2,259 ultra-conserved elements (UCEs). Post-sequencing capture efficiency was tested against 31 marine heterobranchs from major groups, includ- ing Acochlidia, Acteonoidea, Aplysiida, Cephalaspidea, Pleurobranchida, Pteropoda, Runcinida, Sacoglossa, and Umbraculida. The combined Trinity and Velvet assemblies recovered up to 2,211 UCEs in Tectipleura and up to 1,978 in Nudipleura, the most distantly related taxon to our core study group. Total alignment length was 525,599 bp and contained 52% informative sites and 21% missing data. Maximum-likelihood and Bayesian inference approaches recovered the monophyly of all orders tested as well as the larger clades Nudipleura, Panpulmonata, and Euopisthobranchia. The successful enrichment of diversely preserved material and DNA concentrations demonstrate the polyvalent nature of UCEs, and the universality of the probe set designed. We believe this probe set will enable multiple, interesting lines of research, that will benefit from an inexpensive and largely informative tool that will, additionally, benefit from the access to museum collections to gather genomic data.
    [Show full text]
  • A New Phylogeny of the Cephalaspidea (Gastropoda: Heterobranchia) Based on Expanded Taxon Sampling and Gene Markers Q ⇑ Trond R
    Molecular Phylogenetics and Evolution 89 (2015) 130–150 Contents lists available at ScienceDirect Molecular Phylogenetics and Evolution journal homepage: www.elsevier.com/locate/ympev A new phylogeny of the Cephalaspidea (Gastropoda: Heterobranchia) based on expanded taxon sampling and gene markers q ⇑ Trond R. Oskars a, , Philippe Bouchet b, Manuel António E. Malaquias a a Phylogenetic Systematics and Evolution Research Group, Section of Taxonomy and Evolution, Department of Natural History, University Museum of Bergen, University of Bergen, PB 7800, 5020 Bergen, Norway b Muséum National d’Histoire Naturelle, UMR 7205, ISyEB, 55 rue de Buffon, F-75231 Paris cedex 05, France article info abstract Article history: The Cephalaspidea is a diverse marine clade of euthyneuran gastropods with many groups still known Received 28 November 2014 largely from shells or scant anatomical data. The definition of the group and the relationships between Revised 14 March 2015 members has been hampered by the difficulty of establishing sound synapomorphies, but the advent Accepted 8 April 2015 of molecular phylogenetics is helping to change significantly this situation. Yet, because of limited taxon Available online 24 April 2015 sampling and few genetic markers employed in previous studies, many questions about the sister rela- tionships and monophyletic status of several families remained open. Keywords: In this study 109 species of Cephalaspidea were included covering 100% of traditional family-level Gastropoda diversity (12 families) and 50% of all genera (33 genera). Bayesian and maximum likelihood phylogenet- Euthyneura Bubble snails ics analyses based on two mitochondrial (COI, 16S rRNA) and two nuclear gene markers (28S rRNA and Cephalaspids Histone-3) were used to infer the relationships of Cephalaspidea.
    [Show full text]
  • On the Origin of Cryptic Species: Insights from the Stygocapitella Species Complex
    On the Origin of Cryptic Species: Insights from the Stygocapitella species complex José Cerca Thesis submitted for the degree of Philosophiae Doctor Natural History Museum Faculty of Mathematics and Natural Sciences University of Oslo 2019 "The beauty and brilliancy of this insect are indescribable, and none but a naturalist can understand the intense excitement I experienced when I at length captured it. On taking it out of my net and opening the glorious wings, my heart began to beat violently, the blood rushed to my head, and I felt much more like fainting than I have done when in apprehension of immediate death. I had a headache the rest of the day, so great was the excitement produced by what will appear to most people a very inadequate cause." Alfred Russel Wallace “Em cada esquina um amigo, em cada rosto igualdade.” (In each corner a friend, in each face equality) José Afonso – Zeca “Não sou nada. Nunca serei nada. Não posso querer ser nada. À parte disso, tenho em mim todos os sonhos do mundo.” (I am nobody. I will never be anything. I cannot desire to be anything. Other than this, I hold every dream in the world.) Fernando Pessoa Contents Acknowledgements Page 1 List of manuscripts and appendices included Page 5 Summary Page 7 Introduction Page 9 Methods and materials Page 13 Main findings and Discussion Page 21 References Page 46 Manuscripts and appendices Page 57 José Cerca – On the Origin of Cryptic Species: Insights from the Stygocapitella species complex Acknowledgments I belong to a lineage from Portugal’s rural interior.
    [Show full text]
  • Provisional Agenda
    CBD Distr. GENERAL UNEP/CBD/SBSTTA/20/INF/24* 11 April 2016 ENGLISH ONLY SUBSIDIARY BODY ON SCIENTIFIC, TECHNICAL AND TECHNOLOGICAL ADVICE Twentieth meeting Montreal, Canada, 25-30 April 2016 Item 4.1 of the provisional agenda** REPORT OF THE REGIONAL WORKSHOP TO FACILITATE THE DESCRIPTION OF ECOLOGICALLY OR BIOLOGICALLY SIGNIFICANT MARINE AREAS IN THE SEAS OF EAST ASIA1 INTRODUCTION 1. At its tenth meeting, the Conference of the Parties to the Convention on Biological Diversity requested the Executive Secretary to work with Parties and other Governments as well as competent organizations and regional initiatives, such as the Food and Agriculture Organization of the United Nations (FAO), regional seas conventions and action plans, and, where appropriate, regional fisheries management organizations (RFMOs) to organize, including the setting of terms of reference, a series of regional workshops, with a primary objective to facilitate the description of ecologically or biologically significant marine areas through the application of scientific criteria in annex I of decision IX/20 as well as other relevant compatible and complementary nationally and intergovernmentally agreed scientific criteria, as well as the scientific guidance on the identification of marine areas beyond national jurisdiction, which meet the scientific criteria in annex I to decision IX/20 (paragraph 36 of decision X/29). 2. In the same decision, the Conference of the Parties requested that the Executive Secretary make available the scientific and technical data, and information and results collated through the workshops referred to above to participating Parties, other Governments, intergovernmental agencies and the Subsidiary Body on Scientific, Technical and Technological Advice (SBSTTA) for their use according to their competencies.
    [Show full text]
  • Review of the Red Sea Phyllidiidae (Gastropoda: Nudibranchia)
    Cilia patterns and pores: Comparative external SEM examination of acochlidian opisthobranch gastropods Jörger, Katharina; Neusser, Timea; Schrödl, Michael Zoologische Staatssammlung München, Münchhausenstr. 21, 81247 München, Germany; Email: [email protected], [email protected], [email protected] INTRODUCTION Acochlidians are a morphologically and biologically extremely diverse group of opisthobranch gastropods, ranging from mesopsammic “dwarfs” (1.0 - 5.0 mm) to limnic “giants” (up to 3.5 cm). Only limited information is available for the 27 valid species, concerning their anatomy, biology and reproduction, while their external morphology is fairly well described. Pervious scanning electron microscopical (SEM) examinations of entire acochlidians, such as Asperspina riseri (Morse, 1976) or Pontohedyle milaschewitchii (Kowalevsky, 1901) by Morse (1976) and Wawra (1986) however indicated that body surface structures still offer a variety of new characters for phylogenetic and taxonomic analyses. MATERIAL AND METHODS Several specimens of 8 marine and 2 limnic species were dehydrated in graded ethanol followed by a graded acetone series. The specimens were critical-point-dried in 100% acetone in a Baltec CPD 030 and coated with gold in a Polaron Sputter Coater for 120 sec. SEM examinations were conducted using LEO 1430VP SEM at 10-15kV. B Figure 3: Ciliation pattern on head and head appendages. A. Hedylopsis spiculifera with a constant overall ciliation. B. Asperspina murmanica with dense ciliation on the dorsal head region and less dense on the head appendages. C. Pontohedyle milaschewitchii with two defined ciliary bands on the oral tentacles an a third one crossing the head transversally. D. Microhedyle glandulifera (Kowalevsky, 1901) with only scattered bundles of cilia.
    [Show full text]
  • From Sea to Land and Beyond–New Insights Into the Evolution of Euthyneuran Gastropoda (Mollusca)
    BMC Evolutionary Biology BioMed Central Research article Open Access From sea to land and beyond – New insights into the evolution of euthyneuran Gastropoda (Mollusca) Annette Klussmann-Kolb*1, Angela Dinapoli1, Kerstin Kuhn1, Bruno Streit1 and Christian Albrecht1,2 Address: 1Institute for Ecology, Evolution and Diversity, Biosciences, J. W. Goethe-University, 60054 Frankfurt am Main, Germany and 2Department of Animal Ecology and Systematics, Justus Liebig University, Giessen, Germany Email: Annette Klussmann-Kolb* - [email protected]; Angela Dinapoli - [email protected]; Kerstin Kuhn - [email protected]; Bruno Streit - [email protected]; Christian Albrecht - [email protected] giessen.de * Corresponding author Published: 25 February 2008 Received: 2 August 2007 Accepted: 25 February 2008 BMC Evolutionary Biology 2008, 8:57 doi:10.1186/1471-2148-8-57 This article is available from: http://www.biomedcentral.com/1471-2148/8/57 © 2008 Klussmann-Kolb et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Background: The Euthyneura are considered to be the most successful and diverse group of Gastropoda. Phylogenetically, they are riven with controversy. Previous morphology-based phylogenetic studies have been greatly hampered by rampant parallelism in morphological characters or by incomplete taxon sampling. Based on sequences of nuclear 18S rRNA and 28S rRNA as well as mitochondrial 16S rRNA and COI DNA from 56 taxa, we reconstructed the phylogeny of Euthyneura utilising Maximum Likelihood and Bayesian inference methods.
    [Show full text]
  • How to Describe a Cryptic Species? Practical Challenges of Molecular Taxonomy Katharina M Jörger1,2* and Michael Schrödl1,2
    Jörger and Schrödl Frontiers in Zoology 2013, 10:59 http://www.frontiersinzoology.com/content/10/1/59 RESEARCH Open Access How to describe a cryptic species? Practical challenges of molecular taxonomy Katharina M Jörger1,2* and Michael Schrödl1,2 Abstract Background: Molecular methods of species delineation are rapidly developing and widely considered as fast and efficient means to discover species and face the ‘taxonomic impediment’ in times of biodiversity crisis. So far, however, this form of DNA taxonomy frequently remains incomplete, lacking the final step of formal species description, thus enhancing rather than reducing impediments in taxonomy. DNA sequence information contributes valuable diagnostic characters and –at least for cryptic species – could even serve as the backbone of a taxonomic description. To this end solutions for a number of practical problems must be found, including a way in which molecular data can be presented to fulfill the formal requirements every description must meet. Multi-gene barcoding and a combined molecular species delineation approach recently revealed a radiation of at least 12 more or less cryptic species in the marine meiofaunal slug genus Pontohedyle (Acochlidia, Heterobranchia). All identified candidate species are well delimited by a consensus across different methods based on mitochondrial and nuclear markers. Results: The detailed microanatomical redescription of Pontohedyle verrucosa provided in the present paper does not reveal reliable characters for diagnosing even the two major clades identified within the genus on molecular data. We thus characterize three previously valid Pontohedyle species based on four genetic markers (mitochondrial cytochrome c oxidase subunit I, 16S rRNA, nuclear 28S and 18S rRNA) and formally describe nine cryptic new species (P.
    [Show full text]
  • Grey Nomenclature Needs Rules
    Research Article ISSN 2336-9744 (online) | ISSN 2337-0173 (print) The journal is available on line at www.biotaxa.org/em Grey nomenclature needs rules ALESSANDRO MINELLI Department of Biology, University of Padova, Via Ugo Bassi 58 B, I 35131 Padova, Italy; E-mail: [email protected] Received 15 November 2016 │ Accepted 18 January 2017 │ Published online 20 January 2017. Abstract Intentional departures from Linnaean nomenclature are common, and are due to different causes, including deliberate refusal to obey a specific rule of the Code, full rejection of Linnaean nomenclature in favour of an alternative system, use of formulae for special kinds of organisms and especially the use of informal names, or formulae, for kinds of organisms provisionally recognized as corresponding to still undescribed species, whose actual description and naming are reserved for a subsequent study. Special attention should be paid to the mixed usage of names and formulae in the BOLD and GenBank databases. Save for BINs in the BOLD databases, that are an excellent example of how to create and use non-Linnaean formulae for segments of biological diversity, the other kinds of grey nomenclature are seriously faulty in three respects: first, the lack of rules for the creation and usage of these names or formulae precludes unambiguous understanding of what the name or formula is for; second, it is often unclear, especially in database entries, if the alphanumeric specifiers added to a genus name, or even to a Linnaean binomen, are intended to provide unambiguous labelling of a single specimen, or of a taxon, or both; third, and most important, because of the subjectivity of the criteria according to which these non-Linnaean names are created and used, it is generally impossible to compare them across studies, or databases.
    [Show full text]
  • Molecular Phylogeny of the Euthyneura (Mollusca, Gastropoda) with Special Focus on Opisthobranchia As a Framework for Reconstruction of Evolution of Diet
    Thalassas, 27 (2): 121-154 An International Journal of Marine Sciences MOLECULAR PHYLOGENY OF THE EUTHYNEURA (MOLLUSCA, GASTROPODA) WITH SPECIAL FOCUS ON OPISTHOBRANCHIA AS A FRAMEWORK FOR RECONSTRUCTION OF EVOLUTION OF DIET KATRIN GÖBBELER(1,*) & ANNETTE KLUSSMANN-KOLB(1) Key words: character evolution, BayesTraits, molecular systematics, diet, herbivory, Euthyneura ABSTRACT Based on the presented data monophyly of Opisthobranchia is clearly rejected. However, The Opisthobranchia comprise a group of highly monophyly of the Euthyneura (comprising specialized gastropods with uncertain systematic Opisthobranchia and Pulmonata) is supported. affinities. Moreover, monophyly of the whole clade Furthermore, monophyly of most subgroups is has been repeatedly questioned. The present study revealed. The Runcinacea are found as a separate presents the currently most extensive analyses on clade clustering apart from the remaining opisthobranch phylogeny including 58 species from Cephalaspidea, the taxon in which they have been all major subgroups. A combination of four gene formerly classified. Furthermore, Aplysiomorpha markers as well as diverse molecular systematic and Pteropoda are recovered as a monophyletic analytical approaches are applied in order to shed new clade, while the Aplysiomorpha are found to be light on the evolution of this taxon. Special emphasis paraphyletic due to the position of a single taxon. is given to the reconstruction of ancestral diet In addition, Cylindrobullida are revealed as part of preferences since extant Opisthobranchia feed on a the sacoglossan subclade Oxynoacea denying their variety of different food items and the development of current separate status. The enigmatic Acochlidiacea dietary specialization is supposed to be important for are revealed as sister group to Eupulmonata. the evolution of these enigmatic marine gastropods.
    [Show full text]
  • Mollusques Marins De Polynésie Française
    Revue d’Ecologie (Terre et Vie), Vol. 72 (3), 2017 : 215-257 BIOGÉOGRAPHIE DES MOLLUSQUES MARINS DE POLYNÉSIE FRANÇAISE 1* 2 Bernard SALVAT & Jean TRÖNDLÉ 1 PSL ‒ EPHE-CNRS-UPVD USR 3278, CRIOBE, Laboratoire d’Excellence « Corail », Université de Perpignan, Av. Paul Alduy - 66860 Perpignan cedex, France. E-mail: [email protected] 2 17 Rue Girounet, 24130 La Force, France. Correspondant du Muséum national d’Histoire naturelle de Paris, Consultant CRIOBE. E-mail: [email protected] * Auteur correspondant SUMMARY.— Biogeography of French Polynesia marine molluscs.— The distribution of marine molluscs in each of the five archipelagos composing French Polynesia is presented with reference to 2053 species perfectly identified to the specific rank. The progress of knowledge on the distribution of molluscs and the limits of the inventory presented are discussed in relation to the reality of biodiversity. The species richness by archipelago is established and shows a degree of impoverishment along a longitudinal axis, from the Society to the Tuamotu and the Gambier, and along a latitudinal axis from north to south, from the Marquesas to the Society and the Austral. The distribution of species of marine molluscs allows to establish the species specific to each archipelago and those that are common to two or more archipelagos, which together determine the affinities between the archipelagos. The Marquesas and the Austral are very original in comparison with the Society, while the Tuamotu and even the Gambier are only impoverished faunas of the Society. The endemism in French Polynesia is 11.8 % (243 endemics out of 2053 species identified). Beyond this regional rate we can precise by archipelago two levels of endemism: that which is strict for the species whose distribution is limited to this archipelago and that which includes all the endemics, the strict ones and those present in at least one other archipelago: Marquesas (9.3 and 13.6 %) - Austral (6.8 and 12 %) - Society (2 and 6.5 %) - Tuamotu (2.3 and 7.9 %) - Gambier , 7 and 4.8 %).
    [Show full text]
  • Undersized and Underestimated: 3D Visualization of the Mediterranean Interstitial Acochlidian Gastropod Pontohedyle Milaschewitchii (Kowalevsky, 1901) Katharina M
    ARTICLE IN PRESS Organisms, Diversity & Evolution 8 (2008) 194–214 www.elsevier.de/ode Undersized and underestimated: 3D visualization of the Mediterranean interstitial acochlidian gastropod Pontohedyle milaschewitchii (Kowalevsky, 1901) Katharina M. Jo¨ rgera,b,Ã, Timea P. Neussera,b, Gerhard Haszprunara,b, Michael Schro¨ dla,b aZoologische Staatssammlung Mu¨nchen, Mu¨nchhausenstr. 21, 81247 Mu¨nchen, Germany bDepartment Biology I, Ludwig-Maximilians-Universita¨t, Mu¨nchen, Germany Received 25 April 2007; accepted 24 September 2007 Abstract Pontohedyle milaschewitchii (Kowalevsky, 1901) is one of the most common mesopsammic opisthobranchs in the Mediterranean and Black Seas and has been considered as a comparably well-described acochlidian species. However, data on its complex internal anatomy were fragmentary and little detailed due to inadequate methodology available, and contradictory between different sources. The present study redescribes all major organ systems of P. milaschewitchii in full detail by three-dimensional reconstruction from serial semithin sections using AMIRA software. The prepharyngeal central nervous system (cns) of P. milaschewitchii is highly concentrated and shows a euthyneurous and epiathroid condition. Contrary to earlier reports, the cerebral and pleural ganglia are not fused. Aggregations of precerebral accessory ganglia can be grouped into three complexes supplied by distinct cerebral nerves. Rhinophoral ganglia with thin, double cerebro-rhinophoral connectives are described for the first time in acochlidians. A Hancock’s organ is present in the form of a conspicuous, curved fold in the epidermis posterior to the oral tentacles. Cerebral nervous features and sensory structures are discussed comparatively. Our study confirms P. milaschewitchii as having the male genital opening in an unusual position above the mouth.
    [Show full text]
  • How to Describe a Cryptic Species? Practical Challenges of Molecular Taxonomy Katharina M Jörger1,2* and Michael Schrödl1,2
    Jörger and Schrödl Frontiers in Zoology 2013, 10:59 http://www.frontiersinzoology.com/content/10/1/59 RESEARCH Open Access How to describe a cryptic species? Practical challenges of molecular taxonomy Katharina M Jörger1,2* and Michael Schrödl1,2 Abstract Background: Molecular methods of species delineation are rapidly developing and widely considered as fast and efficient means to discover species and face the ‘taxonomic impediment’ in times of biodiversity crisis. So far, however, this form of DNA taxonomy frequently remains incomplete, lacking the final step of formal species description, thus enhancing rather than reducing impediments in taxonomy. DNA sequence information contributes valuable diagnostic characters and –at least for cryptic species – could even serve as the backbone of a taxonomic description. To this end solutions for a number of practical problems must be found, including a way in which molecular data can be presented to fulfill the formal requirements every description must meet. Multi-gene barcoding and a combined molecular species delineation approach recently revealed a radiation of at least 12 more or less cryptic species in the marine meiofaunal slug genus Pontohedyle (Acochlidia, Heterobranchia). All identified candidate species are well delimited by a consensus across different methods based on mitochondrial and nuclear markers. Results: The detailed microanatomical redescription of Pontohedyle verrucosa provided in the present paper does not reveal reliable characters for diagnosing even the two major clades identified within the genus on molecular data. We thus characterize three previously valid Pontohedyle species based on four genetic markers (mitochondrial cytochrome c oxidase subunit I, 16S rRNA, nuclear 28S and 18S rRNA) and formally describe nine cryptic new species (P.
    [Show full text]